Nice read, I understand how you feel.
I started myself 15 years ago, but I have the chance to not have to use so many APIs or libraries.
The main projects we have are done in-house and we usually have the option to write the libs ourselves, because it's better for maintainability.
I remember that lib I made, to support vertical writing in Chrome for Japanese.
The same CSS couldn't be used because Microsoft is the only one supporting vertical text correctly. (what a surprise! really!)
I handled different browsers and versions (iPad, Safari, Chrome) and made so you could even display tables (by recreating them while rotating all the cells).
All in JS and with a bit of CSS.
It was hard, but it was fun, it's in prod for many years now, and we add features to it from time to time.
That is the part of my job that I like the most.